Healthy Vegetation

Band combination: NIR, SWIR1, Blue

The vegetation in the band combination is highly reflective because of the chlorophyll, and the NIR composite vividly indicates vegetation in various shades. Soils vary from light to dark brown, clouds, snow, ice, are light cyan and the urban areas are shown in cyan blue. Coniferous trees appear darker than the hardwoods. Usually, the deep hues indicate healthier vegetation and/or broadleaf whereas lighter tone indicates sparsely vegetated areas or grasslands. Water and water bodies’ looks very dark, because of the energy absorption in the shortwave infrared and near IR bands.

Healthy vegetation appears in shades of reds, oranges, yellows, and browns. Urban features are white soils can be in browns and green, bright blue, cyan and gray areas represent clear-cut areas, and reddish areas show new vegetation growth and presumably sparse grasslands. Clear and deep water is dark in the combination, and if the water contains sediments or is shallow, it would appear as shades of lighter blue. For vegetation studies, the addition of the SWR1 band increases the sensitivity of identifying plant growth; however, it must be taken care when interpreting the image if the acquisition closely follows precipitation. The combination is not good for studying cultural features for instance roads and runways etc.

To detect healthy vegetation using this band combination is easy because the spectral reflectance curve of a healthy green vegetation has a significant low reflectance in the electromagnetic spectrum visible portion which comes from the plants leaves pigments. The Reflectance increases vividly in the near infrared. Stressed or sparse vegetation can also be identified because they have a considerably low reflectance in the infrared.

The band combination has separated water body from drylands. It has also enhanced existence of moisture in the vegetation. Water bodies appear as dark tone. Both band 5 and band 6 have a high moisture sensitivity to content variation in vegetation and soils. This band is very useful for plant vigor investigations and crop-drought studies.